Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L59/00—Thermal insulation in general
  • F16L59/14—Arrangements for the insulation of pipes or pipe systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L11/00—Hoses, i.e. flexible pipes
  • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
  • F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L9/00—Rigid pipes
  • F16L9/12—Rigid pipes of plastics with or without reinforcement
  • F16L9/133—Rigid pipes of plastics with or without reinforcement the walls consisting of two layers

Definitions

• the innermost barrier layer is designed to contain the fluid or gas.
• the barrier wall will experience excessive localized over-bending, which can cause structural damage to the barrier layer and result in failure of the pipe.
• Fig. 1 is an isometric view of a pipe according to an embodiment of the invention.
• Figs. 2A, 2B, 3 and 4 are enlarged transverse sectional views of the pipe of Fig. 1, depicting various collapsed modes.
• Fig. 5 is an enlarged longitudinal sectional view of the pipe of Fig. 1.
• Fig. 6 is an isometric view of a pipe according to an alternate embodiment of the invention.
• the reference numeral 10 refers, in general, to a pipe according to an embodiment of the invention.
• the pipe 10 is designed to receive a fluid at one end for the purpose of transporting the fluid.
• the pipe 10 includes a barrier layer 12 and an inner layer 14 disposed within the barrier layer in a coaxial relation thereto, with the inner layer normally conforming to the corresponding inner surface of the barrier layer in an abutting relationship, for the entire length of the latter layer.
• the barrier layer 12 can be fabricated from a material that has reasonable ductility and elasticity such as a plastic or elastic polymer.
• the material forming the inner layer 14 can also be a plastic or elastic polymer, and preferably is selected so that it has sufficient ductility to survive after being subjected to large strain levels a number of times, and sufficient elasticity to tend to recover from a collapsed state when the pipe is repressurized.
• the wall thickness of the inner layer 14 relative to the wall thickness of the layer 12 is selected so that damage to the barrier layer 12 is prevented when both the barrier layer and the inner layer are collapsed in response to a hydrostatic load placed on the pipe.
• the layers 12 and 14 are fabricated from a polymer material as discussed above, their relatively thicknesses are selected so that, when the pipe 10 collapses under a hydrostatic load, a maximum strain on the layer 12 will occur that is no greater than approximately 7% which is below the value that will cause damage to the barrier layer for most polymer material.
• the thickness of the inner layer 14 relative to the thickness of the layer 12 is selected to limit the bending of the outer layer to within safe levels of strain.
• the thickness of the inner layer 14 relative to the barrier layer 12 can vary from a value in which the former is less or greater than the latter based on the relative dimensions of the layers 12 and 14 and the material of the layers.
• the relative thicknesses of the layers 12 and 14 shown in the drawing are for the purposes of a non-limitative example only.
• Figs. 2 A and 2B depict the pipe 10 after application of an external pressure to the barrier surface of the barrier layer 12 sufficient to collapse the pipe, hi the case of Fig. 2A, one area of the pipe 10 has collapsed, whereas in Fig. 2B, diametrically opposite portions have collapsed.
• the outer radius R of the inner layer 14 forms a cushion that limits the bending of the barrier layer 12 at an area where the maximum strain on the barrier layer normally occurs.
• the thickness of the inner layer 14 is selected so that the maximum possible bending of the barrier layer 12 is limited to an amount less than the bending that would cause strain on the barrier layer sufficient to damage it.
• the pipe may be further forced into a post- buckled mode shown in Fig. 3.
• one portion of the barrier layer 12 and the inner layer 14 attain maximum deformation, and the collapse is such that the flow path through the inner layer 14 is completely closed.
• the collapsed inner layer 14 forms a cushion with round radii R which limit the maximum possible bending of the barrier layer 12 and thus protect it from damage.
• the collapse of the pipe 10 can also result in small gaps G at two ends of the cross section of the pipe, as shown in Fig. 4.
• the collapsed barrier layer 12 and inner layer 14 form a cushion with round radii R where the maximum strain on the barrier layer occurs.
• the radii R will be greater than the radii R in the example of Fig. 3.
• relative lower strain is expected on the barrier layer 12.
• the inner layer 14 can suffer localized structural damage, such as crazing or localized yielding, especially after several collapses, but this damage will not affect the function of the pipe and can be tolerated.
• the inner layer 14 When the inner layer 14 is, in fact, damaged, it functions as a sacrificial layer.
• the accumulation of permeated fluid and/or gas in the interface between the barrier layer 12 and inner layer 14 can cause separation between the barrier layer 12 and inner layer 14 prior to collapse of the pipe 10. This separation could result in an undesirable collapse mode other than those shown in Fig. 2 and 3 since the inner layer 14 may not be able to protect the barrier layer from over-bending and subsequent structural damage.
• a technique to eliminate this accumulation and thus to insure that the pipe 10 collapses properly to the collapse modes (shapes) shown in Fig. 2 and 3 is depicted in Fig. 5.
• a series of small radially-extending and axially and angularly-spaced holes 14a are formed through the inner layer 14 in any known manner, such as by drilling.
• the holes 14a will promote the flow of the trapped fluid/gas from the interface F, and into the interior of the inner layer 14 as shown by the solid arrows. This is caused by two effects - a "vacuum” effect due to low pressure at the inner side of the holes 14a which is generated by the flowing fluid/gas inside the inner layer 14 in the direction shown by the dashed arrow, and a “squeezing" effect as the internal flow pressure (with possible external pressure on the outer surface of the inner layer 12) pushes the inner layer 14 and the barrier layer 12 against each other.
• the pipe 10 thus can tolerate relatively high hydrostatic pressures while eliminating the disadvantages of the metallic layers discussed above and avoiding potential structural damage to the barrier layer.
• the pipe 10 can be wound on a storage reel in a collapsed, substantially flat form, an advantage from a storage and transportation standpoint.
• a pipe 20 according to an alternate embodiment is shown in Fig. 6 and is designed to receive a fluid at one end for the purposes of transporting the fluid.
• the pipe 20 includes a barrier layer 22 and an inner layer 24 which are identical to the barrier layer 12 and the inner layer 14, respectively, of the previous embodiment.
• the inner layer 24 is disposed in the barrier layer 22 in a coaxial relation thereto, with the inner layer normally conforming to the corresponding inner surface of the barrier layer in an abutting relationship, for the entire length of the barrier layer.
• a protective layer 26 extends over the barrier layer 22, a reinforcement layer 28 extends over the protective layer 26 and an additional protective layer 30 extends over the layer 28.
• the protective layers 26 and 30 can be made from plastic or elastic polymer, or plastic or elastic polymer tapes with or without reinforcement fibers.
• the reinforcement layer(s) can be made from metallic or composite strips with or without interlocking.
• the pipe 20 thus enjoys all of the advantages of the pipe 10 and, in addition, enjoys additional protection and reinforcement from the layers 26, 28, and 30.
• the pipe can be provided with one or more protective layers and/or one or more reinforcement layers extending over the outer layer.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Rigid Pipes And Flexible Pipes (AREA)
• Laminated Bodies (AREA)

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• 2002
  • 2002-12-17 US US10/321,084 patent/US6926037B2/en not_active Expired - Fee Related
• 2003
  • 2003-12-16 EP EP03808337A patent/EP1573243A2/de not_active Ceased
  • 2003-12-16 AU AU2003302987A patent/AU2003302987A1/en not_active Abandoned
  • 2003-12-16 BR BR0317410-7A patent/BR0317410A/pt not_active IP Right Cessation
  • 2003-12-16 WO PCT/IB2003/006474 patent/WO2004055426A2/en not_active Ceased
• 2005
  • 2005-03-22 US US11/088,620 patent/US7640950B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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